Post by callmerob on Nov 2, 2023 16:56:56 GMT -5
Stumbled across this on Amazon…
Lawnmower blade grinder
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698958673/kvw0uuwzvwrv0njuwnck.jpg)
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698958796/mvfpi6gox5wl6fysvaem.jpg)
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698958839/i47ujydbjnldmp0slfma.jpg)
The company Oregon has been around for awhile. Grampa Cox invented the first good chainsaw in 1947, and they’ve been making tools ever since. This lawnmower blade grinder is a lightweight bench-top model, and it does a lot of things right. Motor is 1/3hp, 1725rpm, 1” motor shaft, 5/8” arbor, swinging an 8” grinding wheel, with vertical adjustment, welded steel frame, switch, plug it in.
But I want a saw more than a grinder. My DIY drop-saw with little toy motors is too slow and feeds too heavy. And isn’t a diamond saw just a skinny grinding wheel anyway? Maybe it could make all those cuts on sphere preforms.
In any case, it has a lot of what a saw needs, already assembled. Priced at $287.
So I bought it.
Couldn’t help myself.
Don’t Drink & Shop, kids.
Replace the grinding wheel with a saw blade. Build a simple vise and sliding table. Push the rock into the blade. Should be fun, yeah?
The raised steel platform means not enough room for a rock, so remove it. We can cut the horizontal braces with a hacksaw, and the welds with a grinder. Must wear eye protection. This is not pretty and is harder than it looks - dirty, noisy, slow, not enough room for either tool. Not nearly as much fun as the movie in my head.
Ok this part is fun.
Grind the weld remnants & repaint.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959171/xw0lusak578slckwpemt.jpg)
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959373/jho0oylutxquxbonegak.jpg)
Base plate & drawer slides
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959508/kmgrtkoz6dhlccpwptbe.jpg)
Sliding table is 1/2” PVC plate.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959633/vm1qknlrspt576ujkgvx.jpg)
Assembled sliding table, drawer slides, vise
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959713/fn8x9blrijjojlgsnlop.jpg)
Saw blade is 8” x 0.080” x 5/8 hole.
Flange washers for a Skil saw.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959800/yfo2mmfhx3u1wq23wo4e.jpg)
Flood coolant is drip irrigation.
Fountain pump in a bucket.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959884/t0du6nieowlgrttfe2w4.jpg)
Scatter shield is heavy steel for a grinding wheel.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959953/smijakly5bohrz0pf4vp.jpg)
Tilt the saw and the table rolls downhill.
Increase the angle to increase the feed force.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698959997/jvnnwdbbymxjffdzkrej.png)
Down an incline the forces are Fgravity, Fparallel, and Fperpendicular. Something sine angle, something cosine angle, something, minus Ffriction, something.
I don’t know if this works but let’s cut a rock, shall we?
3” obsidian rough.
Tiles make a mold.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960086/go5lfwgvivpgh773x6qy.jpg)
Plaster-of-Paris holds it square.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960157/tu3jftzsv1utovpn9vgi.jpg)
All up.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960217/wzpxhjvygxf9ihoacnqm.jpg)
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960267/rof9zcy6bphuyhvfj7dg.jpg)
In the cabinet.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960378/xrfzk2qean7acvjfni3x.jpg)
Rough estimates:
Tilt = ~20 degrees
Feedrate = ~3” per ~3 hours
It keeps hanging up on the flood coolant or a clamp or a hose gets loose or something. Each is a different dumb teething problem. We call it ‘prototype development’ to feel better about it.
Blade is square to the table. Not-quite-a-square measures 3.00” plus/minus 0.10”. Not quite square because of initial setup errors.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960476/rdfi7el0rsk3apcdjpaz.jpg)
Not-quite-a-cube either. Sides are skewed slightly. All 4 sides are square with the table, but not quite square with each other. Table slides may need adjustment, or the motor shimmed, but it may not be enough to matter.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960610/k2wa95y0u3us8nqf2s1x.jpg)
A 3” cube is 4” diagonally, and fixtures add a little more, so raise the motor for clearance. Please see the new position of the red bolts. Add shims to raise the scatter shield.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960688/cavi1o1gfbtq0uqclhzk.jpg)
V-blocks
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960759/kymwsposxmp0xgihyz4j.jpg)
The white shim in the v-block positions the rock for the cut and keeps the v-block clear of the blade.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960834/g2hgrjshgxmojrtptsfr.jpg)
First octagonal cut
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698960946/xoh5gec8tli0pvpzkyh2.jpg)
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698961010/mumx6jrxy0eydc0phdjf.jpg)
Three more cuts make an octagon.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698961085/m2rgzzifqv19yifbkeef.jpg)
Sixteen trim cuts make an octahedron.
Same fixture.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698961155/m9yjpcqrmv856kqqr8p0.jpg)
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698961236/rkuqheid7dezp2lhn4yv.jpg)
The not-quite-an-octahedron.
![](https://res.cloudinary.com/dgpm0t1qm/image/upload/v1698961327/qplkfeyjdlbrke3nitcg.jpg)
(photo is distorted - it looks better IRL)
That’s all the sawing. The preform is hand ground on a diamond wheel to round the sharp corners before it goes to the sphere machine. It’s my first obsidian. You always remember your first obsidian. If you’re interested, here’s a link to the sphere thread….
forum.rocktumblinghobby.com/thread/103840/3-obsidian-sphere
I think the octahedron is uneven because of operator error.
It’s a fun little tilt-saw, and works ok with baseball-size rocks. It is cutting a lot better than the last DIY, and it meets my weird situation where the saw lives in a cabinet on the patio. We will see if the drawer slides survive. WD-40 rinse and fingers crossed.
I like this Black Widow saw blade. The saw is cutting 3” obsidian, and that’s encouraging enough to try some serpentine next. I’m pleased it even works at all.
Tilt-O-Matic.
Hope you like it.
![:)](http://storage.proboards.com/forum/images/smiley/smiley.png)